The present invention relates to a megnetic recording medium and a manufacturing method thereof or, more particularly, the invention relates to a magnetic recording medium having remarkably improved properties such as durability, smooth travelling, weatherability or anti-oxidation resistance and the like manufactured by forming successively a protective layer of a polymer formed by plasma-polymerization of a silane compound and then a lubricating layer of a fluorinated resin on the surface of a metallic magnetic layer.
Heretofore various types of magnetic recording media such as rigid and flexible magnetic recording discs and the like are under development as one of the peripheral devices along with recent development of computers. In recent years, in compliance with the requirement of high-density recording, attention has been concentrated on several types of magnetic recording media of non-binder type including a thin metallic magnetic layer as the magnetic recording element formed by either one of the dry-process vapor-deposition methods including vacuum deposition, sputtering and ion-plating or one of the wet-process metal-plating methods including electroplating, electroless plating and the like, and a great deal of efforts are being directed to this type of magnetic recording media with a desire to bring these recording media into practical use.
There are two classes of the methods for forming a thin metallic magnetic layer on a substrate such as polyester films and the like including the vapor-deposition methods such as vacuum deposition, sputtering, ion-plating and the like and the metal-plating methods such as electroplating, electroless plating and the like. Each of the vapor-deposition methods has several disadvantages such as the low productivity because the manufacturing system is necessarily batch-wise due to the nature of the process which is carried out in a vacuum atmosphere if not to mention the large cost of power consumption for maintaining the atmosphere of vacuum. On the contrary, the methods of metal-plating have an advantages in energy-saving and in productivity since the process is carried out under atmospheric pressure.
On the other hand, the inventors have previously proposed a method of forming a polymer layer having lubricity as the protective layer on various kinds of substrates by the application of a method of plasma-induced vapor-phase deposition using a gaseous mixture composed of amethylhydrogen polysilane and oxygen. The method easily provides a hard layer with lubricity containing silicon carbide and silanol groups and the thin layer exhibits a hydrophilicity on the surface due to the silanol groups contained therein and advantageous results are obtained in the adhesive bonding and wetting of the lubricating layer.
The inventors of the present invention have attained to the present invention after studies on the application of such a thin layer as the protective layer for the thin metallic magnetic layer prepared by the aforementioned metalplating method.